[SOLVED] Difficulty With Minecraft Server

This is another "cant set up a Minecraft server" post ... I hope someone can help. The server works on my computer but it does not work on his.

Both of our computers are wired directly to the ASUS RT-AC86U router via Ethernet cable. His IP address local to the US is 192.168.50.166.

These are the settings for port forwarding:

Service Name: Minecraft Source IP: (blank) Port Range Local IP: 192.168.50.166 Local Port: 25565 TCP: BOTH

He connects to 192.168.50.166 when he runs Minecraft from his own computer. Minecraft servers However when he enters an external IP (obtained from the "Network Map" page of the router settings) this will result in the error:

Failed to connect to the server io.netty.channel.AbstractChannel$AnnotatedConnectException: Connection timed out: no further information

When I attempt to connect from my computer to 192.168.50.166, I get the exact same error message from Minecraft.

But here's the real kicker ... If I run the server on MY computer (192.168.50.48) and change the Local IP port forward settings accordingly, EVERYTHING WORKS. I can connect to the Minecraft server using either my local IP or the external IP.